Topic: Weird DNS stuff going on...

[penguinzrool]

Hi guys,

I've had an SME 6.0.1 box running happily since Christmas. My network has a broadband router connected to the outside world, using NAT and a firewall to protect the local LAN.

The SME box is currently hosting one website, and providing email for 2 domains. Using my domain registration company's DNS management, I've got SMTP email for both domains and the server handling the web requests, all through forwarded ports on the router.

The PCs on the network use DHCP and DNS.

This has been going fine, as I say, since Christmas. Recently, though, something weird has been happening.

Usually, if i run 'ping server' it happily gets replies from 192.168.3.1. However, now it sometimes returns the external IP address of my primary domain, which it isn't even hosting the site for! This is a pain when my IMAP email clients were configured to connect to 'server'.

The odd thing is, a reboot of the PC usually sorts out the addressing, only to mess up later. Ipconfig shows the DNS servers the PCs use are the 2 for my ISP, then the server as the third. Could it be there's some sort of race going on which the server sometimes does and sometimes doesn't win, and what can I do about it?!

Thanks!

[CharlieBrady]

I've had an SME 6.0.1 box running happily since Christmas. My network has a broadband router connected to the outside world, using NAT and a firewall to protect the local LAN.

You'll have way fewer problems, especially DNS problems such as you are currently having, if you sell the router and use the SME box in servergateway mode.

The PCs on the network use DHCP and DNS.

You don't say where they're getting their DHCP leases from. I'll guess the router and not the SME server.

The odd thing is, a reboot of the PC usually sorts out the addressing, only to mess up later. Ipconfig shows the DNS servers the PCs use are the 2 for my ISP, then the server as the third. Could it be there's some sort of race going on which the server sometimes does and sometimes doesn't win, and what can I do about it?!

Not quite. Your PCs have three DNS servers listed. They can use any of them for any query, and they should distribute the queries randomly. So it's no surprise that they sometimes ask your ISP's DNS servers, and get the wrong response.

If my advice to get rid of the router doesn't suit you, then you'll need to change the DHCP server so that only your SME server is listed as a DNS server. One way to do that would be to disable DHCP in the router and enable it in the server. You'll also need to renew the leases in your PCs.

All would have "just worked" out of the box if you used the server in servergateway mode.



Thanks![/quote]

[Janm]

Yes Charlie i agre
Same problem i had when i used
d-link router -without the router
everything is fine-just a little comment
Regards Jan oZ Land

[penguinzrool]

Hey guys, thanks for the answers.

The SME box IS the only DHCP/DNS server on the network - I made sure these were disabled on the router before installing it.

And using SME in server/gateway mode would be nice, but I'd have to invest in a new ADSL modem (I've got a combined modem/router) which the powers that be probably wouldn't like.

Unless anyone knows how to use an Actiontec USB/Ethernet Home DSL Modem and Router in USB mode with SME 6?

[CharlieBrady]

The SME box IS the only DHCP/DNS server on the network - I made sure these were disabled on the router before installing it.

Then you need to work out how the ISP's DNS servers are getting into the picture. They shouldn't be configured in the SME box, and shouldn't be referenced in DNS leases.

And using SME in server/gateway mode would be nice, but I'd have to invest in a new ADSL modem (I've got a combined modem/router) which the powers that be probably wouldn't like.

There's no way to disable the router feature? You can't configure the modem in bridge mode?

[penguinzrool]

Surely the ISP DNS servers need to be put into the SME box on the initial setup screens (when you choose the mode, hostname, etc) otherwise the PCs wouldn't ever get told the numbers by anything? It's the SME box that's providing the workstations with the ISP DNS servers that I gave it on that setup...

As for the modem, I've tried at least 5 times over the past few years to get it running as a modem, and failed spectacularly on all counts. The problem is that UK broadband uses PPPoA to assign the modem/router's IP and authenticate the connection. If you set the Actiontec box to modem mode, there's no option to put in the username and password, because it assumes it's connected to a host PC:



Also, at present I've only got one NIC in the SME box - its in a nice small Aopen case which takes half height PCI cards - anyone know where to get one of these?

Cheers all.

[CharlieBrady]

Surely the ISP DNS servers need to be put into the SME box on the initial setup screens (when you choose the mode, hostname, etc) otherwise the PCs wouldn't ever get told the numbers by anything?

No they don't. The SME server has a DNS resolving server (just like your ISP's servers do), and knows how to query the global DNS starting at the "root" servers. There's no reason to reference your ISP's DNS servers at all, and since they sometimes get things wrong, or have unreliable DNS servers, it's usually best to bypass them.

[penguinzrool]

ok cool, i didnt know that  

will re-run the initial setup through putty, leaving out the external dns servers and see what happens.

thanks!

[penguinzrool]

hmm, went through the original setup and there's no option anywhere to put in other dns servers, so i dont know where the PCs are getting the ISP addresses  

[chris burnat]

hmm, went through the original setup and there's no option anywhere to put in other dns servers

in 6.01, you will find it under "select master DNS server address" which can be accessed from the (admin) server console under item 2. "configure this server". Should be blank - no entires.

[penguinzrool]

yeah, i went through those server configuration screens before and the dns servers aren't in there. weirdly, a reboot of the server after doing that about a week ago cured it temporarily, but the problem's now come back.

running ipconfig /flushdns, ipconfig /release and ipconfig /renew sorts it when a desktop's playing up but it's still a bit of a pain.

anyway, i've ordered a nice half height second NIC and we'll see how it copes in server/gateway mode.

there isn't anyone out there who would know how to set up an actiontec home modem/router for static routing is there?!

[janusgj]

I was forced to find a new DSL location for a SME server that had been running great for about 3 years. Much to my dismay it won't communicate with the Actiontech DSL/modem router provided by my ISP. I assigned a useable static IP,(71.39.2.209)A subnet mask of (255.255.255.248) reserved gateway IP (71.39.2.214) assigned by Qwest and, nothing.
when I use www.showmemyip.com The gateway address (71.39.2.214) is reported. Not the IP reserved Network IP (71.39.2.208) or the reserved Broadcast ip (71.39.2.215). In all instances the SME server reports that the connection to the internet has failed. I cannot ping any of the addresses. However, I do see the SME server from the workstations on the internal NIC. Any ideas?

[turnip]

And using SME in server/gateway mode would be nice, but I'd have to invest in a new ADSL modem (I've got a combined modem/router) which the powers that be probably wouldn't like.

There's no way to disable the router feature? You can't configure the modem in bridge mode?[/quote]

You don't need to. Just make the SME box the only thing behind the router, and have the router forward the ports you need on to the SME box (or use the router's 'DMZ' feature, which forwards everything onto one machine). This is called double NAT.